1. Field of the Invention
The present invention relates to an electromagnetic drive device which can be used as an indicator device for registering the magnitude of a measurement. A plurality of indicator devices of the present invention are particularly useful as gauges and meters in a display panel, for example, of the kind used in an automobile instrument cluster fitted into a dashboard. Such gauges can include the speedometer, fuel gauge, tachometer, oil pressure gauge, alternator or charging gauge, and the like.
2. Prior Art
Currently, gauge movement in many analogue-type indicator devices of the kind typically used in an instrument cluster is provided by an air coil mechanism that drives a "pointer." This is well known to those skilled in the art. The pointer is a complex mechanism itself that must be dynamically balanced after assembly to conform to the low torque output of its associated air coil. The air coil is mounted in an instrument cluster housing and the housing is fitted into the dashboard. However, air coil movement suffers from gauge inaccuracy characterized by pointer drift, pointer imbalance (despite dynamic balancing), pointer stutter, non-linearity throughout the motion range, poor response time, return to zero problems, stop pin requirements and high power requirements.